Technical Field
The present disclosure relates to an aircraft, and more particularly, to an aircraft having a mounting assembly for mounting a portion of an engine exhaust duct in an opening in an airframe panel.
Description of Related Art
Certain aircraft have main power units in or on a wing. Oftentimes the main power units, such as a gas turbine engine, are exhausted directly from the aft end of the wing. In some aircraft, an auxiliary power unit, which is typically a smaller gas turbine engine, is exhausted using a metal exhaust duct that is mounted internally cantilevered from a metal firewall in the fuselage. The exhaust duct extends from the firewall through an opening provided in an outer airframe surface panel where hot (e.g. 1200° F.) turbine exhaust gases (e.g. 1200° F. exhaust gases) are discharged to atmosphere.
In order to thermally protect the airframe panel from the hot exhaust duct, the opening in the airframe surface panel currently is over-sized to provide a clearance space between the hot exhaust duct and the airframe surface panel. However, the over-sized opening in the airframe surface panel can weaken the airframe panel and create drag that adversely affects aerodynamics of the outer airframe panel during aircraft operation.
There is a need for an improved mounting for the exhaust duct on the airframe panel of such tiltrotor and other aircraft.